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sivacha

Junior Member

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India

flicker noise of the down mixer
Oct 30^th, 2006, 3:38am

hi
while designing the down mixer(active, folded mixer), iam facing a serious and well known difficulty with the flicker noise of the input switches.
Gain, noise figure and linearity are conflicting with each other.
Gain increases----> noise figure improved ------> linearity is lost.
Could you please suggest the good optimization for these??
Receiver:: Low IF type
Freq range of operation:: 2.4GHz

thank you...

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aaron_do

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Re: flicker noise of the down mixer
Reply #1 - Oct 30^th, 2006, 8:45pm

How low is your IF? If it is above 1 MHz you should be able to avoid the flicker noise problem. Gain NF and Linearity always conflict. I suggest you optimize based on your receiver requirements (i.e. for what purpose?). You will need some idea of all the other stages performance also (channel select filter, VGA etc)

Aaron

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there is no energy in matter other than that received from the environment - Nikola Tesla

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sivacha Junior Member Offline Posts: 17 India	Re: flicker noise of the down mixer Reply #2 - Oct 30^th, 2006, 9:48pm aaron_do, my IF is 1MHz. this receiver is for BT2.0 Enhanced Data Rates. my main concern is the flicker noise of the LO switches.
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aaron_do

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Re: flicker noise of the down mixer
Reply #3 - Oct 31^st, 2006, 4:50am

I don't really know anything about your system of the bluetooth 2.0 specs. I asked a question previously about system NF calculation and found this paper very helpful. Its posted in the link:

http://www.designers-guide.org/Forum/YaBB.pl?num=1157358393

based on your system specs you can estimate the required gain, NF and linearity.

hope it helps,
Aaron

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there is no energy in matter other than that received from the environment - Nikola Tesla

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